Method for the measurement of pinking in internal-combustion engines



R VICHNIEVSKY METHOD FOR THE MEASUREMENT OF PINKING IN INTERNAL-COMBUSTl ON ENGINES Filed June 25, 1945 IGNITION 1 VOL AGE SOURCE OF"IONIZATION VOLTAGE ION IZATION CURRENT METER 6 NQ EE l N V E NTORQCST/SLA l/ V/CHN/EVS/(V AGENTS Patented Feb. 27, 1951 UNITED STATESOFFICE METHOD FOR THE MEASUREMENT OF PINK- ING IN INTERNAL-COMBUSTIONENGINES Application June 25, 1945, Serial No. 601,532 In France May 11,1944 Section 1, Public Law 690, August 8, 1946 Patent expires May 11,1964 3 Claims.

A limit is set by pinking, that is, by the shock phenomena which appearin internal combustion engines, for each fuel, to the compression ratio,the pressure and temperature of the air admitted into the cylinders, thecooling temperature or the percentage of the mixture, and it is agreedgenerally to classify the fuels depending on their pinking propertiesaccording to what has been called the octane number scale. Methods andequipments have been devised for the determination, as a function of thevariation of one of the engine setting parameters, of the moment whenpinking appears and even of the intensity of such pinking.

However, the beginning of the said phenomenon is not always easy toperceive, the methods used allow too much place for the appreciation ofthe persons who use them, or else, where they provide for betteraccuracy, they can be applied only on special engines operated in welldefined conditions and running at comparatively low speed. Now, theclassification obtained in a given motor will not necessarily beretained in another; likewise, pinking can set in sooner in certaincylinders than in others of the same motor. Consequently, it isnecessary that methods should be devised and equipment designed whichcan be used for measuring pinking in any desired cylinder of any givenmotor, irrespective of its running speed.

This invention has for its object a method and an arrangement for themeasurement of pinking which can be used in the said conditions as wellon conventional test motors for refining the theoretic fuel grading ason any one of the cylinders of a motor in use for the ascertainment ofthe real behaviour of each fuel in the motor considered, in eithernormal or abnomal operation and, as far as an airplane motor isconcerned, both in ground-level and flying operation.

It is well known that if a potential difference be created between apair of points located in a gas mass 9. current can set in through thelatter, the intensity of which is a function of its degree ofionisation. This property has already been taken advantage of forstudying flame propagation in engine cylinders, since the jump in theintensity of the ionisation current which appears between the two pointsat the moment when the latter are reached by the hot gases allowsascertainment of the passing of the flame at the level of the tell-taleplug carrying the pair of points and connected with a suitable detectordevice.

Figure 1 of the drawing represents a typical curve showing ionisationcurrent during combustion,

Figure 2 shows an arrangement for carrying out the method of detectingpinking.

It has now been found, according to this invention, that if theintensity of the ionisation current thus generated be recorded inaccordance with time or the angle of rotation of the crank or any othervariable related with the latter, the curve of the current of ionisationin normal combustion conditions shows only one maximum correspondingeach time to a combustion, whereas in pinking conditions of operationthe first maximum is followed by an additional maximum the value ofwhich is a measure the intensity of the pinking. Figure 1 illustratesthe appearance of the curve of the current of ionisation in non-pinkingconditions with one single peak 5 and in pinking conditions with twosuccessive peaks 2 and 3; the consideration of the curve of intensity ofthe current of ionisation thus provides a method whereby the setting inof pinking can be detected definitely and even its intensity can bemeasured.

The researches of the applicant have revealed that for the purpose ofbringing the phenomenon to view and of obtaining values that areindependent of the shape of the cylinder head a condition which is oneof the peculiarities of this invention is that the electrodes of thetell-tale plug should be located as close as possible to the sparkingplug. Effectively, the appearance of the said additional peak can beexplained by the crossing of the tell-tale plug electrodes by thecompression wave created at the spontaneous ig nition of the mass of yetunburnt gases; at some points in the cylinder head said wave may happento reach the wall at the same time as the flame, or even before, and theadditional peak then can be concealed or inexistent where the tell-taleplug is located at the said point. On the contrary, close to thesparking plug, the flame wave will certainly sweep the tell-tale plugbefore the same is reached by the compression wave propagating throughthe already burnt gases.

In the performance of this method one is led to construct a tell-taleplug comprising a pair of insulated electrodes, or one insulated and oneearthed electrode, where an auxiliary plug boss is available directlyadjacent to the sparking plug boss. A plug boss or a special socket canalso be conceived, according to this invention, which will allow toinsert two separate plugs, viz.: the normal sparking plug and thetell-tale plug. Advantageously however, as a preferred embodiment ofthis invention, a special plug can be provided which, as shown incross-sectional view in Fig. 2,

comprises a pair of insulated electrodes 4, 5 and a pair of earthedelectrodes 6, 1, the ignition being taken care of by the spark whichpasses between the electrode 4 and the earthed electrode 6 adjusted tothe normal gap, while the electrode 5 and the other earthed electrode I,adjusted to a somewhat wider gap, provide the tell-tale element betweenthe points of which the current of ionisation is established. Thesparking and telltale plug then can be constructed as shown in Fig. 2,the sparking electrode being connected with the normal ignition circuitby a central terminal 8 while the tell-tale electrode is connected bymeans of collar 9 in circuit with a source of ionising potential [0 andan indicating or recording instrument II for the measurement of thecurrent of ionisation. It is to be understood that this embodiment isgiven only by way of example and that the invention covers all thearrangements leading to the same result, that is, to provide, either intwo plugs placed very near one relatively to the other, or preferably inone and the same plug, the points serving for the passage of theignition spark and the points between which the ionisation current isestablished, whose intensity depends on what is happening in the gap ofthe tell-tale element.

What I claim as my invention and desire to secure by Letters Patent is:

1. A method for measuring the pinking in a cylinder of an internalcombustion engine, consisting in producing inside the gaseous masscontained inside the cylinder an ionisation current the intensity ofwhich is constant for predetermined temperature and pressure conditionsof the gaseous mass and measuring the variations of the said intensitythroughout the course of a cycle of operation of the engine, whichvariations are significative of detonation.

2. A method for measuring the pinking in a cylinder of an internalcombustion engine, consisting in producing inside the gaseous masscontained inside the cylinder an ionisation current the intensity ofwhich is constant for predetermined temperature and pressure conditionsof the gaseous mass, recording in the form of a curve the variations ofintensity of said ionisation current throughout the cycle, a maximum ofwhich corresponds with the ignition of the gaseous mass and measuring onsaid curve the second maximum following the maximum considered anddefining the value of the pinking.

3. A method for measuring the pinking in a cylinder of an internalcombustion engine, consisting in producing inside the gaseous masscontained inside the cylinder and in the immediate vicinity of the pointat which the ignition of the gaseous mass begins an ionisation currentthe intensity of which is constant for predetermined temperature andpressure conditions of the gaseous mass and measuring the variations ofsaid intensity throughout the cycle for obtaining the value of thepinking.

ROSTISLAV VICHNIEVSKY.

REFERENCES CITED The following references are of record in the file ofthis :patent:

UNITED STATES PATENTS Number Name Date 1,861,021 Martin May 31, 19322,082,030 Schrader et al June 1, 1937 2,113,376 Janco Apr. 5, 19382,202,900 Draper June 4, 1940 2,306,372 Banks Dec. 29, 1942 2,324,458Peters et a1 July 13, 1943

